a. Field of the Invention
The instant invention is directed toward a needle and a system suitable for use in a medical procedure. The instant invention includes a needle where an electrically insulative outer layer is disposed over a portion of an outer surface of the needle, and a distal section of the needle is exposed to allow for mapping of the needle during a medical procedure.
b. Background Art
In an electrophysiology (EP) procedure, electrode catheters may be guided into the chambers of the heart and to strategic places along the heart's conduction system. The electrodes may then be used to record the electrical impulses of the heart and may define the location of abnormal electrical activity. EP procedures may be used to diagnose and treat ventricular tachycardia (VT) or atrial fibrillation (Afib) ablation, for example. One EP procedure is catheter ablation in which a catheter is inserted through the vasculature and into the heart, and energy is delivered through the catheter to that portion of the heart muscle that has been identified as causing an abnormal heart rhythm in order to ablate the tissue (e.g., to disconnect the pathway that is producing the abnormal rhythm).
Catheter ablation may be achieved epicardially without an incision into the chest cavity. In one technique for achieving percutaneous access into the pericardium (i.e., the membranous sac enclosing the heart), a hypodermic needle may be inserted into the chest cavity. The needle may be designed to facilitate entry into the space separating the pericardium and the heart surface (i.e., lift the pericardial sac). This procedure to access the pericardial space may eliminate the need to navigate tortuous vessels or fragile valves and may reduce risk of clot formation. The epicardium is the inner serous layer of the pericardium, lying directly upon the heart.
The needle may be inserted through tissue at the subxiphoid region and advanced toward the right ventricular apex. As the needle approaches the heart under fluoroscopic guidance, small amounts of contrast media (e.g., fluoroscope dye) are injected to document penetration of the needle tip into the pericardial space. Positioning of the needle is associated with layering of the contrast in the pericardial space. The needle tip may be advanced within a few centimeters from a cardiac silhouette (e.g., as seen on fluoroscopy) and then positioned for puncture of the pericardium. Fluoroscopy may reveal a V-shaped indentation (e.g., tenting) of the pericardium with contrast media injection just prior to pericardial puncture, and with puncture the contrast media may highlight the pericardium. The contrast media may be used to confirm the location of the needle by providing a particular “splash” configuration.
The use of fluoroscopy for achieving pericardial access has several potential limitations. Fluoroscopy provides only a two-dimensional image. Furthermore, fluoroscopy does not provide a clear image. In addition, the use of contrast in connection with fluoroscopy merely allows physicians to visualize a boundary for the heart and other tissue, rather than have direct visualization of the needle and the heart. Due to these limitations, epicardial procedures can be time consuming. Also, there remains a risk of puncturing a coronary artery or puncturing a heart chamber. In particular, there remains the risk of ventricular puncture (i.e., puncture in the ventricular wall) and bleeding (e.g., bleeding in the pericardial space).
Thus, there is a need for a system for mapping the location of a needle used for procedures, such as an epicardial procedure, including a needle configured for accurate mapping of the location of the needle tip.